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Lower back pain in the Adventurethoner

Thanks again to Daina Clark (Senior Podiatrist and Bootcamp Instructor) for this article on lower back pain.

back painDo you suffer lower back pain when Adventurethon’ing on the mountain bike? Well you are not alone. A Norwegian study in 2010 of 109 elite cyclists found that over the course of a year, 58% of them had performance limiting lower back pain. A mate of mine always helpfully reminds me to ‘keep the rubber bits down’ when I MTB ride thus avoiding those pesky traumatic injuries that happens when you forget to do so. The back pain I’m talking about though is not from having a stack but from overuse.

 

Lower back pain on the MTB can be caused by a number of factors including your position on the bike, leg length differences, strength or mobility deficits and sometimes it can be caused by what sounds a bit fancy, viscoelastic creep of the passive support structures.

Let’s go through them one by one.

Bike set up can play a big part in lower back pain. The most obvious place to start looking is the saddle height. A saddle that is too high will cause over reaching at the bottom of the pedal stroke. This leads to rocking of the pelvis from side to side and can definitely contribute to pain in the lower back. Have your saddle at a height where you can maintain constant connection with your sit bones and stop the rock’n’roll

Conversely a saddle that is too low will cause you to ride in exaggerated hip and knee flexed position. This can contribute to lower back pain with overactivity of the psoas muscle functioning in  shortened length – a hip flexor that attaches to the lumbar spine. Tightness in the psoas can causing pulling on your lumbar spine and resultant pain.

ct scanTo ride a bike, which is a symmetrical piece of equipment, ideally riders would also be symmetrical. Unfortunately this is seldom the case. Most people have one leg  longer than the other. And while you can get away with up to a 10mm difference when walking, on a bike even a small 2-3mm difference can create asymmetry and  pelvic tilting downwards at the bottom of the pedals stroke on the short limb side. Trying to measure the legs with a tape measure is inherently flawed – if a leg length difference is a suspected cause of lower back pain then measuring the legs on a CT scan can reveal, down to the millimetre, what the discrepancy is. A shim under the short leg cleat will improve symmetry.  It can be a bit tricky to walk in a MTB shoe with a shim under the cleat so plan to ride those tough hills, no push biking allowed!

 

 

This image above shows a CT scan of a rider with a 14.1mm longer left femur compared to the right femur. A recipe for back pain on the MTB.

lumbarAnother study in 2012 looked at cyclists who experienced lower back pain and compared them to those who rode pain free. The main difference between the bike set ups of the two groups was that those who had lower back pain had their saddle tilted nose up by, on average, 3 degrees. If the nose of your saddle is tipped upwards you tend to ride with a posterior pelvic tilt which in turn leads to increase lumbar flexion. Picture a Slumpy McGlumpy sitting with a curved lumbar spine on their saddle. Tight hamstrings can also lead to posterior pelvic tilting, lumbar flexion and potential lower back pain. We will talk more about lumbar flexion later on.

 

Sitting has been recently labelled the new smoking in terms of its negative affects on our health. The problem with excessive sitting, be it in the car, at work in front of a computer, at home in front of the tele, or even on our bike, is that we are spending all our time in a hip flexed position. What happens then is we lose our ability to extend the hip. All that time in hip flexion can severely impact on our ability to use or contract our biggest muscle of the body , our Gluteus Maximus. This results in quad dominance on the bike, stomping when pedalling with poor gluteal activation and resultant poor stability on the saddle. Plus the glutes can contribute up to 50 % of the power to the pedal. So if your glutes are not firing properly not only do you get back pain but you are not riding as fast or as strong as you could be. We’ve got to stand more often when not on the bike, strengthen our lazy butts and start cracking walnuts.

 

Viscoelastic creep is an interesting potential cause of lower back pain on the bike. Have you ever, or maybe you’ve seen one of your friends, get off the bike after a longer ride and have trouble standing up straight? The rider flexes over with their back bent forwards for a while, hands on knees until eventually the stiffness subsides and they can stand tall again. This can be caused by ‘flexion intolerance’. Studies have shown that being in sustained lumbar flexion (think riding a bike for 2 hrs + with a curved lower back, posterior pelvic tilt) can cause viscoelastic creep of the vertebral discs.

Imagine I had a rubber band , I stretched it and then let it go immediately. The rubber band would return to its original length. But if I got the same rubber band and stretched it under high load for 2 hours – what would happen then?  When I let it go it would remain elongated, out of shape and not very useful. That is viscoelastic creep and what is potentially happening to our vertebral discs and ligaments when we spend more than 2 hours on our bike in lumbar flexion.  Avoid getting into a flexed lumbar spine position by being super strong through the core. Also spend time in and out of the saddle, which should be happening on a MTB anyway, and don’t be stuck like glue in one position for too long.

As you can see there are a lot of potential causes for lower back pain on the bike – so what are the  best bets to avoid this painful condition?

Start cracking walnuts with your glutes, improve your hip, psoas  and hamstring mobility, get your saddle height and position sorted and if you think you might have one short leg get it measured properly.

 

Train Smart, Ride Strong

 

Daina Clark (Senior Podiatrist & Bootcamp Instructor)

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